U.S. patent application number 13/276495 was filed with the patent office on 2012-04-26 for aircraft cover including means for limiting the scoop phenomena of pneumatic type.
This patent application is currently assigned to AIRBUS OPERATIONS (S.A.S). Invention is credited to Frederic CHELIN, Alain PORTE, Thierry SURPLY.
Application Number | 20120097261 13/276495 |
Document ID | / |
Family ID | 44063282 |
Filed Date | 2012-04-26 |
United States Patent
Application |
20120097261 |
Kind Code |
A1 |
PORTE; Alain ; et
al. |
April 26, 2012 |
AIRCRAFT COVER INCLUDING MEANS FOR LIMITING THE SCOOP PHENOMENA OF
PNEUMATIC TYPE
Abstract
An aircraft nacelle includes at its outside wall a cowl moveable
relative to the nacelle so as to block or unblock an opening. The
cowl includes an articulation and locking/unlocking elements
distant from the upstream edge of the cowl that include elements
for limiting the appearance of scooping phenomena. The limiting
elements include at least one lock integral with the rest of the
nacelle or respectively the cowl that can occupy a locked state in
which part of the lock interferes with the cowl or respectively the
rest of the nacelle and prevents a deformation that includes a
radial component of the cowl, and another free state in which the
part no longer interferes with the cowl or respectively the rest of
the nacelle and allows the opening movement of the cowl, with the
switch from one state to the next being generated by a gas pressure
variation.
Inventors: |
PORTE; Alain; (Colomiers,
FR) ; CHELIN; Frederic; (Encausse, FR) ;
SURPLY; Thierry; (Cornebarrieu, FR) |
Assignee: |
AIRBUS OPERATIONS (S.A.S)
Toulouse
FR
|
Family ID: |
44063282 |
Appl. No.: |
13/276495 |
Filed: |
October 19, 2011 |
Current U.S.
Class: |
137/15.1 |
Current CPC
Class: |
B64D 29/08 20130101;
F02C 7/20 20130101; Y10T 137/0536 20150401; F01D 25/24 20130101;
B64D 29/06 20130101 |
Class at
Publication: |
137/15.1 |
International
Class: |
F02K 3/04 20060101
F02K003/04 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 26, 2010 |
FR |
10 58784 |
Claims
1. Aircraft nacelle (10) that at its outside wall comprises a cowl
(14) that can move relative to the rest of the nacelle (10) in such
a way as to block or unblock an opening, whereby said cowl (14)
comprises an articulation (15) relative to the rest of the nacelle
(10) and locking/unlocking means (17) distant from the upstream
edge (18) of said cowl (14) that comprises means (19) for limiting
the appearance of scooping phenomena, characterized in that said
means (19) for limiting the appearance of the scooping phenomenon
comprise at least one lock (26) that is integral with the rest of
the nacelle (10) or respectively the cowl (14) that can occupy a
so-called locked state in which a part of the lock (26) interferes
with the cowl (14) or respectively the rest of the nacelle (10) and
prevents a deformation that comprises a radial component of said
cowl (14) and another so-called free state in which said part of
the lock (26) no longer interferes with the cowl (14) or
respectively the rest of the nacelle (10) and allows the opening
movement of said cowl (14), with the switch from one state to the
next being generated by a pressure variation of a gas.
2. Aircraft nacelle according to claim 1, wherein it comprises a
membrane (44) that extends over at least a part of the edge that is
upstream from the opening, which is immobilized in a radial
direction relative to the frame of the opening and which, when the
pressure that is applied on the membrane (44) exceeds a certain
threshold, works with a groove (60) that is made on at least one
part of the edge that is upstream from the cowl (14) and open
toward the front of the nacelle (10).
3. Aircraft nacelle according to claim 2, wherein it comprises a
groove (62) at the frame of the opening, opposite the groove (60),
for immobilizing the membrane (44) relative to the frame in the
radial direction.
4. Aircraft nacelle according to claim 1, wherein the lock (26)
comprises a rod (28) that is guided in translation in a direction
that is contained in a longitudinal plane and that makes an angle
that is greater than 60.degree. relative to the radial
direction.
5. Aircraft nacelle according to claim 4, wherein the lock (26) is
integral with a membrane (44) and comes in the form of a rod (28)
that may or may not work with an opening (36) that is made in a
wall (38) that is integral with the cowl (14).
6. Aircraft nacelle according to claim 5, wherein the membrane (44)
comes in the form of a bellows that is made of an elastic
material.
7. Aircraft nacelle according to claim 4, wherein it comprises
return means (42) for keeping the lock (26) in the free state and a
control supplied with pressurized gas to keep the lock (26) in the
state that is locked against the return means (42).
8. Aircraft nacelle according to claim 7, wherein it comprises a
tap (46) at its outside surface that is connected to the control
for supplying it with pressurized air.
9. Aircraft nacelle according to claim 7, wherein it comprises a
tap (46') at the throat or the engine channel connected to the
control to supply it with pressurized air.
10. Aircraft nacelle according to claim 7, wherein it comprises a
tap (46') at a pressurized duct of the power plant connected to the
control for supplying it with a pressurized gas.
Description
[0001] This invention relates to an aircraft cowl that incorporates
means for limiting pneumatic-type scooping phenomena.
[0002] An aircraft propulsion system comprises a nacelle in which a
power plant that is connected by means of a mast to the rest of the
aircraft is arranged in an essentially concentric manner.
[0003] The nacelle comprises an inside wall that delimits a pipe
with an air intake at the front, with a first part of the incoming
air stream, called the primary stream, passing through the power
plant to take part in the combustion process, and with the second
part of the air stream, called the secondary stream, being
entrained by a fan and flowing into an annular pipe that is
delimited by the inside wall of the nacelle and the outside wall of
the power plant.
[0004] The nacelle also comprises an outside wall with an
essentially circular cross-section that extends from the air intake
to the aft exhaust, constituted by the juxtaposition of several
elements, an essentially rigid air intake at the front followed by
nacelle doors, also called cowls.
[0005] The air intake is rigid because of its curved shapes and
numerous reinforcements for withstanding forces generated by the
aerodynamic flows or possible shocks.
[0006] The cowls are made mobile to allow access to the power plant
that is placed in the interior of the nacelle. These cowls are
articulated with the rest of the nacelle in different manners based
on the kinematics adopted, and they extend from the top of the
nacelle, close to the anchoring of the mast, up to the bottom of
the nacelle, and have a semi-cylindrical shape.
[0007] A cowl generally comprises a piece of sheet metal with
stiffeners on the inside surface to impart a relative rigidity
thereto. The smooth outside surface of the cowl is sensitive to
remaining in the extension of the outside surface of the other
elements, in particular of the air intake, when the cowl is in the
closed position.
[0008] Locking means are provided at the lower edge of the cowl so
as to keep the cowl in the closed position.
[0009] In addition, the frame of the opening that is blocked by the
cowl comprises--on at least a part of its periphery--a contact
surface against which the cowl can rest in such a way as to always
keep its outside surface in the extension of that of the air
intake.
[0010] Optionally, the contact surface of the frame can comprise a
deformable element such as a compressible joint.
[0011] To ensure a positioning of the cowl relative to the rest of
the nacelle along the longitudinal axis that also corresponds to
the pivoting axis of the cowl, and at the upstream and downstream
edges (perpendicular to the pivoting axis) of the frame of the
opening, it is possible to provide shapes that complement the
shapes provided at the upstream and downstream edges of the cowl.
Thus, the upstream (and/or downstream) edge of the frame comprises
a groove, and the upstream (and/or downstream) edge of the cowl
comprises a projecting shape that is housed in the groove that is
provided at the frame. These elements make it possible to guide the
cowl during its closing in such a way that it is correctly
positioned along the pivoting axis when it is closed.
[0012] During flight, considering their relative rigidities, the
cowls can become deformed, in particular in the radial direction,
although the air can penetrate under said cowls into the interior
of the nacelle at the junction with the air intake. This scooping
phenomenon reduces the aerodynamic performance levels of the
aircraft, in particular by increasing the drag, which is manifested
as excessive fuel consumption.
[0013] So as to limit this phenomenon, one approach consists in
increasing the number of stiffeners provided at the cowls. However,
this approach goes against the desired result to the extent that
the addition of stiffeners contributes to increasing the on-board
weight and therefore the consumption of the aircraft.
[0014] According to another alternative, it is possible to provide
a belt system as illustrated in the patent application
FR-2,933,957.
[0015] This invention proposes an alternative to the approaches of
the prior art that limits the scooping phenomena, without
significantly increasing the on-board weight and the maintenance
costs.
[0016] For this purpose, the invention has as its object an
aircraft nacelle that at its outside wall comprises a cowl that can
move relative to the rest of the nacelle in such a way as to block
or unblock an opening, whereby said cowl comprises an articulation
relative to the rest of the nacelle and locking/unlocking means
distant from the upstream edge of said cowl that comprises means
for limiting the appearance of scooping phenomena, characterized in
that said means for limiting the appearance of the scooping
phenomenon comprise at least one lock that is integral with the
rest of the nacelle or respectively the cowl that can occupy a
so-called locked state in which a part of the lock interferes with
the cowl or respectively the rest of the nacelle and prevents a
deformation that comprises a radial component of said cowl and
another so-called free state in which said lock part no longer
interferes with the cowl or respectively the rest of the nacelle
and allows the opening movement of said cowl, with the switch from
one state to the next being generated by a pressure variation of a
gas.
[0017] Other characteristics and advantages will emerge from the
following description of the invention, a description that is
provided only by way of example, relative to the accompanying
drawings in which:
[0018] FIG. 1 is a perspective view that illustrates an aircraft
nacelle,
[0019] FIG. 2A is a cutaway that illustrates the upstream edge of a
cowl of an aircraft nacelle according to a first variant of the
invention in the locked state,
[0020] FIG. 2B is a cutaway that illustrates the upstream edge of a
cowl of an aircraft nacelle according to a first variant of the
invention in the free state,
[0021] FIG. 3 is a cutaway that illustrates the upstream edge of a
cowl of an aircraft nacelle according to another variant of the
invention in the locked state,
[0022] FIG. 4 is a cutaway that illustrates the upstream edge of a
cowl of an aircraft nacelle according to another variant of the
invention in the locked state, and
[0023] FIG. 5 is a cutaway that illustrates the upstream edge of a
cowl of an aircraft nacelle according to a simplified variant of
the invention in a locked state.
[0024] FIG. 1 shows a nacelle 10 that contains a power plant and is
connected to the rest of the aircraft by a mast. It comprises an
outside wall with an essentially circular cross-section that
extends from an air intake 12 to an aft exhaust, constituted by the
juxtaposition of several elements, with an essentially rigid air
intake 12 at the front followed by nacelle doors 14, also called
cowls.
[0025] The cowls 14 comprise an articulation 15 relative to the
rest of the nacelle 10 to make them mobile and to allow access to
the power plant. Thus, these cowls 14 make it possible to block or
unblock an opening that is delimited by a frame.
[0026] These cowls 14 are articulated with the rest of the nacelle
in different manners based on the kinematics adopted, and they
extend from the top of the nacelle, close to the anchoring of the
mast, to the bottom of the nacelle, and have a semi-cylindrical
shape.
[0027] A cowl 14 generally comprises a piece of sheet metal with
stiffeners on the inside surface to impart a relative rigidity
thereto. The smooth outside surface of the cowl is sensitive to
remaining in the extension of the outside surface of the other
elements, in particular of the air intake, when the cowl is in the
closed position.
[0028] Hereinafter, the longitudinal direction corresponds to the
direction of the axis of rotation of the fan of the power plant. A
vertical median plane corresponds to a vertical plane that contains
the longitudinal axis.
[0029] A radial direction is a direction that is perpendicular to
the longitudinal direction.
[0030] A tangential plane at a given point corresponds to a plane
that is perpendicular to the radial direction that passes through
said point.
[0031] The upstream and downstream positions are defined with
reference to the direction of the flow of gases inside the power
plant.
[0032] According to one embodiment, a nacelle comprises two cowls
14 that are symmetrical relative to the vertical median plane of
the nacelle, with each cowl being able to pivot around an axis of
rotation 16 that is oriented in the longitudinal direction and
arranged close to the mast (approximately at 12 o'clock).
[0033] Thus, the cowls 14 can occupy several states, namely a
closed state in which the outside surfaces of the cowls are
arranged in the extension of the surfaces of the parts of the
nacelle that are upstream and downstream from the cowls, and an
open state in which the cowl to pivot allows access to the power
plant.
[0034] The lower edges of the cowls are essentially parallel to the
pivoting axes 16 and are connected to one another in the closed
state by locking/unlocking means 17.
[0035] The nacelle, the cowl(s), and the articulation of the cowl
relative to the rest of the nacelle, and the locking/unlocking
means of the cowl are not described in more detail because they are
known to one skilled in the art.
[0036] The upstream and downstream edges of the cowl connect the
lower and upper edges of the cowl.
[0037] These upstream and downstream edges work with the upstream
and downstream edges of the frame of the opening. Positioning and
guiding means can be provided to position the upstream (or
downstream) edge of the cowl correctly with the upstream (or
downstream) edge of the opening, for example a V-shaped groove at
the edge of the opening that works with a slot that is provided at
the edge of the cowl or blades provided at the edge of the cowl
that work with housings provided at the edge of the opening.
[0038] The positioning means make it possible to ensure the
positioning of the cowl in the direction of the pivoting axis 16 of
the cowl. The invention is not limited to these embodiments. Other
approaches can be considered for positioning the cowl relative to
the opening.
[0039] In all cases, to allow the opening and the closing of the
cowl, the positioning means do not ensure the positioning of the
cowl relative to the rest of the nacelle in a direction that
corresponds to the direction of the opening and closing movement of
the cowl that corresponds essentially to the radial direction.
Consequently, taking into account the distance between the pivoting
axis 16 and the locking/unlocking means 17, the cowl 14 can become
deformed in the radial direction and can produce a scooping
phenomenon.
[0040] So as not to alter its aerodynamic characteristics, the
nacelle comprises means 19 for limiting the deformation of the cowl
and the appearance of the scooping phenomenon.
[0041] FIGS. 2A, 2B, 3 to 5 show in a cutaway--in a plane that
contains the longitudinal axis of the power plant--the upstream
edge 18 of the cowl that works with the upstream edge 20 of the
opening. The latter comprises an offset 22 that makes it possible
to house the end of the edge 18 of the cowl in such a way that the
outside surface of the cowl is arranged in the extension of the
outside surface of the rest of the nacelle.
[0042] The opening is delimited by a frame that comprises a wall 24
at the upstream edge that is perpendicular or tilted relative to
the outside surfaces of the nacelle.
[0043] According to the invention, the means 19 for limiting the
appearance of the scooping phenomenon comprise at least one lock 26
that is integral with the frame of the opening (more generally with
the rest of the nacelle), one part of which is able to occupy a
so-called locked state in which the lock part interferes with the
cowl 14 and prevents a deformation that comprises a radial
component of said cowl and another so-called free state in which
said lock part 26 no longer interferes with the cowl and allows the
opening movement of said cowl.
[0044] According to an important point of the invention, the lock
26 is of the pneumatic type, namely the switch from one state to
the next is generated by a pressure variation of a gas.
[0045] As a variant, the lock could be integral with the cowl.
[0046] If appropriate, the nacelle 10 can comprise one or more
locks 26 arranged in the zones at which the scooping phenomena are
likely to appear, in particular at zones located approximately at 3
o'clock and/or at 9 o'clock.
[0047] According to a first embodiment that is illustrated in FIGS.
2A and 2B, the lock 26 comprises a rod 28 that is guided in
translation by a bearing 30 in the form of a tube that is integral
with the wall 24 of the frame of the opening, whereby said rod 28
moves translationally in a direction that is secant to the radial
direction. Preferably, the rod can move translationally in a
direction that is contained in a longitudinal plane and that makes
an angle of greater than 60.degree. relative to the radial
direction.
[0048] According to the variant that is illustrated in FIGS. 2A and
2B, the bearing 30 is attached at the inside surface of the wall 24
and passes through said wall 24 via an opening 32. The rod 28
comprises a first end 34 that can work with an opening 36 that is
made in a wall 38 that is integral with the cowl.
[0049] The bearing 30, and the openings 32 and 36 are arranged in
such a way as to be aligned when the cowl is closed correctly.
Likewise, the bearing 30 and the opening 36 have cross-sections
that are adapted to those of the rod in such a way that the rod 28
can slide without play or with a very slight play relative to the
bearing 30 and the opening 36.
[0050] Advantageously, the first end 34 is rounded to facilitate
the centering of the rod 28 relative to the opening 36.
[0051] The rod 28 can slide between a first locked state in which
it interferes with the wall 38 and passes through the opening 36
and a second free state in which it does not interfere with the
wall 38 and does not pass through the opening 36.
[0052] At its second end, the rod 28 comprises a collar 40 that
acts as a stop.
[0053] Return means are provided for keeping the rod 28 in the free
state. According to one embodiment, a compression spring 42 is
inserted between the collar 40 and the wall 24 or the bearing
30.
[0054] To ensure the switch from the free state to the locked state
and holding it in the locked state, the nacelle comprises at least
one control.
[0055] According to the variant that is illustrated in FIGS. 2A and
2B, the control is a membrane 44 in the form of a bladder whose
volume can vary based on the pressure that is present in the
interior of said bladder.
[0056] This membrane 44 comprises a part that is inserted between
the second end of the rod 28 and a stop in such a way that the
membrane 44 exerts a force against the return means 42 and
generates the switch to and/or the holding in the locked state of
the rod 28 when the pressure that is applied to the membrane 44 is
greater than a given threshold. Thus, when the pressure in the
interior of the bladder is greater than the given threshold, then
the lock is in the locked state, as illustrated in FIG. 2A. In
contrast, when the pressure inside the bladder is less than a given
threshold, then the lock is in the free state because of the action
of the return means 42, as illustrated in FIG. 2B.
[0057] To ensure the operation of the lock, the nacelle comprises
means for supplying the control with compressed air.
[0058] According to a first variant that is illustrated in FIGS.
2A, 2B and 3, the nacelle--at its outside wall--can comprise a tap
46 that is connected to the bladder 44, whereby said tap is tilted
in such a way as to allow the filling of the bladder when the
aircraft is in flight.
[0059] Thus, the pressure inside the bladder increases with the
speed of the aircraft. This arrangement makes it possible to obtain
a naturally-controlled supply of air. Actually, the switch to the
locked state is done when the speed of the aircraft exceeds a
predetermined value, with the scooping phenomena appearing at
speeds that are greater than said predetermined value.
[0060] According to another variant, the control can be supplied by
another tap 46' (in broken lines in FIGS. 2A, 2B, 3 and 4) by
sampling air at the throat or the engine channel or any other
pressurized gas at pressurized pipes of the power plant. In this
case, it is advisable to provide means 48 for controlling the
supply, for example a motorized valve.
[0061] However, the invention is not limited to the embodiments
specified above but covers all of the variants thereof relative to
the means for supplying the control.
[0062] FIG. 3 showed another variant that is close to the one
described in FIGS. 2A and 2B. According to this variant, the rod 28
can move translationally in a direction that is perpendicular to
the radial direction. According to another difference, the control
comes in the form of a membrane 44 that delimits a cavity into
which pressurized air is injected. The pressure variation in the
interior of said cavity deforms the membrane 44 that then moves the
lock against the return means.
[0063] According to the preceding variants, the lock and the
control are two separate elements.
[0064] FIGS. 4 and 5 show other variants for which the lock and the
control are connected, and a single piece is formed.
[0065] According to the variant that is illustrated in FIG. 4, the
lock is integral with a membrane 44 and comes in the form of a rod
28 that may or may not work with the opening 36 that is made in the
wall 38 that is integral with the cowl 14.
[0066] To ensure the return and its being held in the free state,
the membrane 44 can come in the form of a bellows and can be made
of an elastic material, preferably with shape memory, where the
unstressed shape of the membrane corresponds to that which it
occupies in the free state.
[0067] As for the variant illustrated in FIG. 3, the membrane 44
delimits a cavity 56 that can be supplied with pressurized gas.
When the pressure exceeds a certain threshold in the cavity 56, the
membrane 44 becomes deformed, which is manifested by the engagement
of the rod 28 in the opening 36.
[0068] According to this variant, the lock preferably moves
translationally in a direction that is perpendicular to the radial
direction.
[0069] According to a variant that is illustrated in FIG. 5, the
control and the lock come in the form of a membrane 44 and more
specifically a flange that extends over at least a part of the edge
that is upstream from the opening, which is immobilized in a radial
direction relative to the frame of the opening and which, when the
pressure in the interior of the flange exceeds a certain threshold,
works with a groove 60 that is made on at least a part of the edge
that is upstream from the cowl and open toward the front of the
nacelle and prevents the deformation of said cowl by limiting its
movement in the radial direction.
[0070] Advantageously, the wall 24 of the frame of the opening also
comprises a groove 62 opposite the groove 60 for immobilizing the
flange relative to the frame in the radial direction.
[0071] Thus, when the pressure in the interior of the flange
exceeds a certain threshold, a part of the flange is engaged in the
groove 60 and prevents a radial deformation of the cowl.
[0072] In contrast, when the pressure in the interior of the flange
is not adequate, the flange is not rigid enough to immobilize the
cowl, which can then be maneuvered.
* * * * *